This application is based upon and claims the priority of Japanese Patent Application No. 2000-374894, filed on Dec. 8, 2000, which is hereby incorporated by reference in its entirety.
1. Field of the Invention
The present invention generally relates to exhaust systems for land vehicles. More specifically, the present invention relates to an improved exhaust system layout for snowmobiles that results in improved cooling of the exhaust system.
2. Description of the Related Art
Snowmobiles are powered by internal combustion engines that are mounted within a substantially enclosed engine compartment. The engine compartment typically is defined within a portion of a body panel such that direct airflow through the engine compartment is inhibited.
An exhaust system mounts to the engine for routing exhaust byproducts from the engine to the atmosphere. Generally, the exhaust system mounts to a forward facing portion of the engine and extends forward before wrapping around one side of the engine. In this manner, the exhaust system is mainly disposed forward and to one side of the engine.
Due to the restricted air flow within the engine compartment, the amount of cooling provided by the air is greatly reduced. Thus, the temperature of the exhaust system components tends to be very high. This increased temperature of the exhaust system also results in increased engine temperature and increased air temperature within the engine compartment. For many reasons, such high temperatures are not desired.
Thus, an exhaust system that can reduce the amount of heating within the engine compartment is desired. Additionally, the exhaust system preferably is simply constructed and admits of a rather simple cooling arrangement.
Accordingly, one aspect of the present invention involves a snowmobile comprising a frame assembly comprising an inverted generally U-shaped portion. An engine is mounted to the frame assembly. A drive belt is powered by the engine and disposed at least partially within the inverted generally U-shaped portion. An exhaust system is connected to the engine and extends rearward of the engine in a region defined between a bight of the inverted generally U-shaped portion and the drive belt.
Another aspect of the present invention involves a snowmobile comprising a frame assembly. The frame assembly comprises a front portion and a rear portion that are joined together. The rear portion comprises three walls that combine to form an inverted U-shaped member. The front portion defines an engine compartment with an engine being disposed within the engine compartment. The engine powers a drive track that extends below at least a portion of the inverted U-shaped member. An exhaust system is coupled to the engine and defines a discharge path for exhaust gases generated in the engine. The exhaust system comprises an exhaust conduit that extends between an inner surface of the inverted U-shaped member and the drive track.